E-Follower & P37 By Rod -- It's cool.

papanohn · 20th January 2005, 04:04 AM

I just finished my amp .
E-Follower (by Pavel Macura) drive with Pre (DoZ) P37 By Rod Elliott .

E-Follower
I use IRFP450 & TIP142. (because l have it.

)
Input 1.5/160 WIMA MKP
parallel 4700/50V with 1.5/160 WIMA MKP
Power supply 35 VDC

Pre (DoZ) P37 By Rod Elliott .
Input 1.5/160 WIMA MKP
Power supply 38 VDC

I try direct coupling between Pre & Amp umm.. not difference

It's run hot.
but sound wonderful , very great . and cheap.
many thanks pavel , Rod.

4real · 20th January 2005, 09:37 AM

Well, thaks seems to look nice.

I was planing on using the follower, too, but with an opamp and not the IRF's. Still not sure about it though...

What kind of a PSU did you use?

Can you compare this one with other class A designs?

papanohn · 21st January 2005, 02:40 AM

Hello ,

I use simple PSU (per channel)

For power amp
EI Transformer 28-0 VAC 150 VA
Bridge 25 A
C Elna 10000/50 x4

Preamp
O transformer 36-0 VAC 30 VA
regulated with zener 36V & BD139

my camera just borrowed ,
I will post picture soon..

PMA · 21st January 2005, 10:43 AM

Some of the readers have small troubles with achieving appropriate Iq through R6 (1 Ohm). This is caused by the different ZD3V zener diodes than I use. I strongly recommend for this position the BZX83 3V0 zener diode (0.6W). The bigger diodes have smoother knee of the reverse characteristics, their zener voltage is usually too low in this circuit, resulting in too low Iq. This can be easily measured as a voltage drop across R6.

Another comment is about direct coupling berween the DoZ pre and the follower. This way you lose output power, as there is a 4V voltage shift at MOSFET gate against DoZ output. Both the DoZ dc output voltage and MOSFET Source output voltage should be at +Vs/2 for the highest possible output power. The only way how to get it is to use the coupling capacitor and bias resistor at MOSFET gate, as seen on my web.

Regards,
Pavel

papanohn · 24th January 2005, 03:19 AM

Many thanks ,Pavel.

I 'll try to test.

Regards.

20th January 2005, 04:04 AM	#1
papanohn diyAudio Member Join Date: Jul 2004 Location: Bangok	E-Follower & P37 By Rod -- It's cool. I just finished my amp . E-Follower (by Pavel Macura) drive with Pre (DoZ) P37 By Rod Elliott . E-Follower I use IRFP450 & TIP142. (because l have it. ) Input 1.5/160 WIMA MKP parallel 4700/50V with 1.5/160 WIMA MKP Power supply 35 VDC Pre (DoZ) P37 By Rod Elliott . Input 1.5/160 WIMA MKP Power supply 38 VDC I try direct coupling between Pre & Amp umm.. not difference It's run hot. but sound wonderful , very great . and cheap. many thanks pavel , Rod. __________________ PapaNohn

21st January 2005, 02:40 AM	#3
papanohn diyAudio Member Join Date: Jul 2004 Location: Bangok	Hello , I use simple PSU (per channel) For power amp EI Transformer 28-0 VAC 150 VA Bridge 25 A C Elna 10000/50 x4 Preamp O transformer 36-0 VAC 30 VA regulated with zener 36V & BD139 my camera just borrowed , I will post picture soon.. __________________ PapaNohn

24th January 2005, 03:19 AM	#5
papanohn diyAudio Member Join Date: Jul 2004 Location: Bangok	Many thanks ,Pavel. I 'll try to test. Regards. __________________ PapaNohn

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20th January 2005, 09:37 AM	#2
4real diyAudio Member Join Date: May 2004 Location: Arnhem	Well, thaks seems to look nice. I was planing on using the follower, too, but with an opamp and not the IRF's. Still not sure about it though... What kind of a PSU did you use? Can you compare this one with other class A designs?

21st January 2005, 10:43 AM	#4
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Some of the readers have small troubles with achieving appropriate Iq through R6 (1 Ohm). This is caused by the different ZD3V zener diodes than I use. I strongly recommend for this position the BZX83 3V0 zener diode (0.6W). The bigger diodes have smoother knee of the reverse characteristics, their zener voltage is usually too low in this circuit, resulting in too low Iq. This can be easily measured as a voltage drop across R6. Another comment is about direct coupling berween the DoZ pre and the follower. This way you lose output power, as there is a 4V voltage shift at MOSFET gate against DoZ output. Both the DoZ dc output voltage and MOSFET Source output voltage should be at +Vs/2 for the highest possible output power. The only way how to get it is to use the coupling capacitor and bias resistor at MOSFET gate, as seen on my web. Regards, Pavel

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